Pneumatic percussion tools



Aug.-25;1959 G. 1. EKSTRM mL 9 2,900,959

PNEUMATIC PERCUSSION 'rooLs Filed June 4, 1957 3 Sheets-'Sheet 1 Allg. 25., 1959 G, EKSTRM EVAL 2,900,959

PNEUMATIC PERCUSSION TOOLS Filed June 4, 1957 3 Sheets-Sheet 2 Aug. 25, 1959 G. l. EKSTRM ErAL. 2,900,959

PNEUMATIC PERCUSSION .TOOLS Filed June 4,419.57 3 Sheets-Sheet 3 66 a; g .sa E* yENToRs @y i Mmmm United States Patenti() Applies-risanare'4,'f19s1gfsefia11Nor-s633368 .6 ciaims. "1(c1. 121413) This invention -relates f. tohefzgeneral designzopneumatic percussion :.tools comprising :a= cylinder? casing forming awork-ingcylinder for af differential hammer piston reciprocable within said cylinder under theinilence of compressed air. Such tools, which may be concrete breakers; frock drills 'nii other*- haminerftools-usually comprise a backhead, AaA front head zandone. or more intermediate ca'singswhichtoge'ther' with' -the cylinder easing ','fare stapledf'one npon.the other between saidihealis and "held together by two,or-more.bolts. FfFor yaifiuspurposes passages extend` longitudinally of one or more of said casings and openings are provided for the exhaust of air from the working cylinder and for other purposes. The provision of such passages and openings results in a complicated external shape of the various casings which are usually forgings. In order to avoid unnecessary weight of the casings the external shape of the casings usually shows many projections for accommodating the passages or openings which projections are liable to be exposed to damage in the rough handling to which tools of this kind are often exposed. It is also difcult to keep such tools clean and also the projections may cause difculties for the operator and also transmit vibrations and shocks to the operator. One object of the present invention is to avoid these diculties and to simplify the shape of the various casings, and to reduce manufacturing costs. A further object of the invention is to provide tools of this character which have a smooth external shape and which may easily be kept clean. A further object of the invention is to provide in a simple manner spaces suitable as air receivers and for accommodating mufers or lubricating oil magazines.

For these and other purposes We provide a pneumatic percussion tool comprising a cylinder casing, a working cylinder in said cylinder casing, a differential hammer piston reciprocable in said working cylinder, a valve casing at the rear end of the cylinder casing, an intermediate casing forming a yguide for the small diameter portion of said harrnner piston at the front end of the cylinder casing, a back head, a front head, a tube in which said cylinder casing and said intermediate casing are stapled one upon the other, lands on said cylinder casing cooperating with the inner wall of said tube and having substantially the same outer diameter as the inner diameter of the tube, and bolts connecting said front head and said rear head and pressing said heads and the cylinder casing and intermediate casing axially together within said tube.

In the accompanying drawings three embodiments of pneumatic percussion tools according to the invention are illustrated by way of example. Fig. 1 is a side view and partial longitudinal section of a concrete breaker according to the invention, and Fig. 2 is a section taken on line II-II of Fig. l. Fig. 3 is a second embodiment of a concrete breaker according to the invention, and Fig. 4 is a section taken on line IV-IV of Fig. 3. Fig. 5 is a Side view and partial longitudinal section of a rock drill ice4 according to the invention, 'and Fig: 6- is asectionrtaken on line VI-Vl of Fig. 5.

riIhe concrete-*breaker illlustrated'in Fig.' I `consists of a ai jackf' head 1formingtwo-handles;a"frontrheadv 2, a 5 rylindercasing', 1V'alve -casings'v 4 'and' 5,' an'interr'nediate casing- 61,-f'and a"anvilblockfcasing 7. t'The' cylinder cias- 3- isv provided with lands? 9; and 10, vthe; intermediate 1 'casingfrwith "lands' 'I1-and" 12,?1and': the"casing 7' with a A:.ftland .13. Vhelandswt; 9,:10,: 11,?12 and :131 all? have 1012the=samerextemaldiarrreter and; fit Ewithin a' tubular body .thentherf-wthin the tubular" bodylt between-."theb'ack head2 1 and'front'head 2andarelpressed together by two .:l`Jo1tsr15. A' dilerentialhamnier pistonf16 is reciprocable a-"in afworking cylinder 171tformed`^by the'c'ylinder casing casing 7. 'I'he workingimplementis'indicatdibythe reference numeral 19.1l-Anairreceiver space is formed rebetweenithez'iands Sand 9::and'aniexhaustsilencertspace 20 21 is formed between the lands 9'Va'ndf10'fwithinthe tubular` =bo dy "-14 lwhich nspacef. 'communicates "thr'ough :sports 68 Withaifurthen exhaustchamber'- 69 formedfbetween the lands 11 and1l2i2ndtebinrnunicatingi witlifthe t atr-nosphererthrough ports" (not''tillust`1ated)=frin .-thef" tube 14. An oil reservoir 22 is formed between the lands 12 and 13.l The tubular body 14 has suitable openings (not illustrated) through which air from the working cylinder and the silencer is expelled to the atmosphere.

The tool illustrated in Figs. 3 and 4 is a concrete breaker comprising a back head 25 forming two handles, a front head 26, a valve casing 27, a cylinder casing 28, an intermediate casing 29, and an anvil block casing 30. The cylinder casing 28 is provided with lands 31, 32, 33, and 34 of the same external diameter fitting within a tube 35. The cylinder casing 28 has an internal shoulder 36 by which the casing 28 rests on the intermediate casing 29. A dilerential hammer piston 37 is reciprocable within a working cylinder 38 formed in the cylinder casing 28. An anvil block 39 is fitted in the casing 30. The working implement is indicated by reference numeral 40. The cylinder casing 28, the intermediate casing 29 and the casing 30 are stapled one upon the other within the tube between the front head 26 and the valve casing 27 and the back head 25. Two bolts 41 are arranged longitudinally of the tool for holding the front head and the back head and the casings between them together. An air reservoir 42 is formed between the lands 31 and 32 and a mutier chamber 43 is formed between the lands 32 and 33.. The space 44 between the lands 33 and 34 may be used as an oil reservoir.

It will be appreciated that the external surface of the main portion of the tools shown in Figs. 1 and 3 is completely smooth so that it cannot transmit longitudinal oscillations to the operator when the tube 14 or 35, respectively, during operation rests against the bodyor legs of the operator.

The rock drill illustrated in Figs. 5 and 6 consists of a back head 50, a front head 51, a pall and ratchet mechanism casing 52, a valve casing 53, a cylinder casing 54, an intermediate casing 55 and a chuck casing 56. The casing 52 is provided with lands 57 and 58, the casing 53 with lands 59 and 60, the casing 54 with lands 61 and 62 and the casing 55 with lands 67. The lands 57, 58, 59, 60, 61, 62, and 67 have the same external diameter and t within a tube 63. A hammer piston 64 of the differential type is reciprocable within a working cylinder 65 formed -in the cylinder casing 54. The front and back heads 50 and 51 and the casings 52, 53, 54, 55, and 56 are held together by means of four bolts 66 'which bolts are carried within the tube 63 so that the portion of the rock drill between the back head 50 and 3 the front head 51 has a completely smooth cylindrical shape.

The tools above described should be considered only as examples and the invention may be varied in different ways within the scope of the claims.

What we claim is:

1. A pneumatic percussion tool comprising a cylinder casing, a working cylinder lin said cylinder casing, a diierential hammer piston reciprocable in said working cylinder, a. valve casing at the rear end of the cylinder casing, an intermediate casing forming a guide for the small diameter portion of said hammer piston at the front end of the cylinder casing, a back head, a front head, a tube in which said cylinder casing and said intermediate casing are stapled one upon the other, lands on said cylinder casing cooperating with the inner wall of said tube and having substantially the same outer diameter as the inner diameter of the tube, and bolts connecting said front head and said rear head and pressing said heads and the cylinder casing and intermediate casing axially together within said tube.

2. A pneumatic percussion tool according to claim 1, in which the valve casing is stapled on the cylinder casing within the tube.

3. A pneumatic percussion tool according to claim 1, in which a sleeve enclosing an anvil block is stapled on the front head within the tube.

4. A pneumatic percussion tool according to claim 1,

in which the intermediate casing has two annular continuous lands forming seals with the inner 'wall of the tube and providing an exhaust chamber between them, a further exhaust chamber formed around the cylinder casing, passages in one of said lands forming a communication between said chambers, and ports in the tube forming a communication to the atmosphere from the exhaust chamber between the lands of the intermediate casing.

5. A pneumatic. percussion tool according to claim 3, in which said sleeve has an annular land cooperating with and of substantially the same outer diameter as the diameter of the inner wall of the tube.

6. A pneumatic percussion tool according to claim 1, in which a rst land is provided on the cylinder casing at the rear end thereof, a second annular continuous land on said cylinder casing remote from said first land and confining with said first land and the tube an air accumulation space, and passages through said rst land and the valve casing forming a communication between said space and the inlet to the Working chamber of the cylinder.

References Cited in the le of this patent UNITED STATES PATENTS 1,866,819 Renfer July 12, 1932 1,881,258 Bayles Oct. 4, 1932 

